Spatial-temporal Analysis of Gummosis in Three Cashew Clones at Northeastern Brazil

Abstract

The cashew gummosis caused by the fungus Lasiodiplodia theobromae is one of the most important disease of cashew in the northeast of Brazil. The lack of studies about method of early detection, pathogen dissemination, host predisposition, mechanisms of attack and defence and efficient control measures assures this disease as a limiting factor as to growing of cashew under semi-arid conditions. Therefore, the characterization of spatial patterns of gummosis development under commercial orchards may provide important insights into the mechanisms involving in dissemination and disease progress of this disease, as well as in the understanding of dynamic of host, pathogen and environmental interactions for this pathossystem. This work aimed to characterize gummosis temporal and special dynamics in three commercial orchards of cashew clones of cashew with different levels of susceptibility by studying the special arrangement of diseased plants. Disease incidence and severity, quantified determined by a descriptive scale in clones BRS 226 (resistant), Embrapa 51 (slightly resistant) and Faga 11 (susceptible) in a commercial orchard located in Pio IX district (Piaui state, Brazil), were monitored and mapped. Data were collected within three blocks of 90 plants for each clone. Indices of dispersion were estimated to study the spatial dynamic. The dynamics and structure of gummosis foci were also analysed. As expected, data showed different degrees of gummosis incidence and severity for the three clones. Even under different levels of disease, a random dispersion pattern model of dispersion could be observed at the beginning of epidemic for all clones. However, as disease develops, a clustered model is likely to fit. The increase in disease incidence resulted from the increasing in both focus number and size.

Diseases of Cashew Nut Plants (Anacardium Occidentale L.) in Burkina Faso

“…Our results are consistent with those of Freire et al [10] and Araújo [4]. Some studies revealed that fungi are responsible of gummosis [6].According to this author, up to now, despite the important damage induced by gummosis disease on cashew, no efficient measure is available to control it. Many authors reported an increase in gummosis severity in all north-eastern producing states in Brazil [6-7-17].…”

“…Unfortunately, cashew is threatened by many biotic and abiotic constraints resulting in significant yield losses. Among biotic constraints, diseases and pests are the most damaging and compromise the cashew nut yield in terms of quality and quantity [4][5][6][7][8][9][10][11][12][13][14][15]. Indeed, more than 12 diseases were reported to infect cashew tree worldwide.…”

Effects of pre‐ and post‐treatment with ethephon on gum formation of peach gummosis caused by Lasiodiplodia theobromae

“…Gummosis, which is a common response to pathogen infection, wounding or insect attack, is the process of gum accumulation and exudation in some plant species, such as tulip, grape hyacinth, cashew and the stone fruit tree species of Rosaceae (Saniewski et al ., ; Cysne et al ., ; Miyamoto et al ., ). Peach gummosis, caused by Botryosphaeria spp.…”

Polyclonal antibody‐based ELISA in combination with specific PCR amplification of internal transcribed spacer regions for the detection and quantitation of Lasiodiplodia theobromae, causal agent of gummosis in cashew nut plants

“…Samples were collected in Pio IX county (state of Piauí, Brazil) from the branches and leaves of naturally infected cashew plants of the commercial clone CCP‐76. This cashew orchard has been studied and proven to be infested by L. theobromae (Cysne et al ., ), and infected plants exhibited different severities of gummosis. Plants with no symptoms were also collected.…”